The invention relates to a method for producing a composite sheet metal part having at least one metallic region from a composite sheet metal blank which has two outer cover sheets of metal and at least one layer which is arranged between the cover sheets and consists of a plastics material. The invention also relates to a forming tool for producing a corresponding composite sheet metal part from a composite sheet metal blank.
Composite sheet metal parts are frequently used in the form of a sandwich sheet which has two outer cover sheets and a non-metallic layer which usually consists of plastics material and is arranged between the cover sheets. One reason for the increasing use of composite sheet metal parts is that these parts can have characteristics which, in the case of a solid material sheet, are often mutually exclusive. For example, a composite sheet metal part locally allows very good rigidities, in spite of its low weight, and at the same time can provide very good sound absorbing properties. However, many uses require these composite sheet metal parts to be joined with other sheet metal parts or metal parts. The joining methods such as fusion welding and soldering, frequently used for metal sheets, give rise to problems, however, due to the high heat supply thereof. When there is a high heat supply, the composite sheet metal part can be impaired in that the non-metallic layer or plastics layer arranged between the cover sheets is damaged. Consequently, it is often quite difficult to produce a sufficiently good join between a composite sheet metal part and a metal part. Various approaches have been tried hitherto to solve this problem. Japanese patent application JP 06-087079 A teaches preparing the region of a composite sheet metal part used for joining to further parts, for a welded joint in that the region of the composite sheet metal part is initially heated, the two outer cover sheets are bent up in the peripheral region and the plastics layer arranged between the cover sheets is removed using abrasive means. Thereafter, the cover sheets of the peripheral region are welded together, thereby providing a composite sheet metal part which has a metallic region, i.e. a region which has substantially no plastics layer and which can be used for the usual joining methods. However, this method is very complex and cannot be easily automated.
On this basis, the object of the invention is to provide a method and a forming tool by which complex formed composite sheet metal parts can be easily produced in a few steps and which still have metallic regions.